Islam is very strict about morality. There are clear cut rules devised by ALLAH swt on moral values. Back biting is considered one of the biggest sins. It is one of those sins, whose punishment is made known to us. ALLAH swt has stopped Muslims from doing this act on many places in Quran.
O you who believe! Avoid much suspicions, indeed some suspicions are sins. And spy not, neither backbite one another. Would one of you like to eat the flesh of his dead brother? You would hate it (so hate Back Biting). And fear Allah. Verily, Allah is the One Who accepts repentance, Most Merciful.
In this noble verse, ALLAH swt has equated backbiting with eating flesh of a dead person. This is the best explanation of this moral illness. Just like the prospect of eating flesh of a dead person, particularly, eating flesh of a dead brother is so hateful, so does talking behind the back of a person. This verse explains another aspect of back biting. Just like is almost impossible in most cases to hurt a person physically when he is alive but easy when he is dead, telling a person that he is bad is difficult but easy when he is not around.
Back biting is common. Whenever people sit and talk, mostly there talk drifts towards backbiting. They make fun of people, how they walk, how they talk, and then it goes towards what bad a person has in him. Such talks are never confined and they eventually reach the concerned person. This kind of thing is so hurtful. No one of us likes to know how bad we are, from other people. Islam protects the feelings of the people and anything that hurts others is not liked in Islam. Swear punishment for back biting in hereafter has been mentioned in following hadith.
SUNAN ABU-DAWUD, Book 41, Number 4860:
Narrated Anas ibn Malik:
The Prophet (peace be upon him) said: When I was taken up to heaven I passed by people who had nails of copper and were scratching their faces and their breasts. I said: Who are these people, Gabriel? He replied: They are those who were given to back biting and who aspersed people's honor.
This tradition tells us that backbiting does not only hurt others on personal level but also means dishonoring them in front of non-concerned people. For these reasons, avoid back biting. do not discuss people instead talk about Islam and emaan boosters.